The Perfect Date by R. L. Stine (Fear Street)

After his girlfriend's gruesome death one year ago, Brady is finally ready to get on with his life. He's met Rosha and he's fallen hard. But he's also fallen into trouble. Terrible accidents seem to happen whenever Rosha's around. And a strange figure with a scarred face is following Brady everywhere he goes. Is Rosha really Brady's dream girl? Or has she brought his worst nightmare back to life?